Digitally navigating a 3-dimensional space traditionally is a lean-forward experience: one need to actively interact with the environment and control which way to go. While this is feasible, and even logical in certain scenarios such as gaming, it does pose an issue for lean-back scenarios such as watching a free-to-roam 3d concert or a 3d movie. Also pseudo-3d use cases such as multi-view video with user-selectable views suffer from this issue. One needs to be engaged with the content by means of an additional explicit control input (gamepad, keyboard, mouse, etc). This is not always desirable.
The advent of affordable virtual reality devices such as the Oculus Rift emphasizes this issue. It is not enough to wear the Virtual Reality glasses, but one also needs some control method to navigate in the 3d world. This is not acceptable for many lean-back scenarios
Solutions exist that allow continuous navigation in a 3d space by moving towards the location that you are looking at. The location to which the user is looking is either determined by a gaze tracking device or is automatically available in the case of Virtual Reality goggles. The applicability of this solution is very limited however due to the continuous movement throughout the scene.
Something that is more feasible, especially for lean-back scenarios, is the limitation of spatial movement to a number of so-called navigation points. Instead of allowing free navigation through the 3d scene, the user is limited to navigating to one of these navigation points.
The selection of a navigation point occurs when watching the point for a sufficiently long time. When the user continues to watch the navigation point, a visual indicator appears that he or she will jump to that point in a short while. The user can still look away at that point in order to cancel the navigation.
In this process of selection of navigation points, there is a timing mechanism for activating a navigation point a user is navigating to, which process includes three stages in the navigation point activation. The initialization delay is the first stage and occurs when the viewing angle is within the appropriate range of a navigation point, but the visual countdown indicator is not shown yet. The second stage initializes the activation point and activates this visual countdown indicator. This is also the cue for the user that, if he or she continues looking in that direction, the viewpoint will jump to that navigation point. Whether or not the user takes an action can be seen as implicit feedback to the system. The third stage activates the activation point by moving to that particular location. One can note here that this is feedback to the system that the activation was actually wanted, otherwise it is the assumption is that the user would have looked away in order to cancel the navigation point activation.
Still a problem of such solution is that unwanted activation of the timing mechanism happens a lot, e.g. when watching content, it is quite feasible that a user simply wants to watch and factually watches in the direction of the navigation point without actual intent to navigate into that direction.